A statistical method for eliminating the data pertaining to accidental grains from fission track dating data

A method of statistically excluding the data pertaining to accidental grains from the fission track age data is proposed. In the population method, the ratio F of the observed coefficient of variation of the number of spontaneous tracks and its expected coefficient should be close to 1 if the experimental set of mineral grains contains no accidental grains of different ages. When the F value is considerably larger than 1, the calculations of the ratio F are repeated and the data pertaining to the grain whose number of spontaneous tracks is largest are progressively discarded, until it becomes almost 1. The remaining grain would then be essential ones. On the other hand, in the case of the grain by grain method, the ratio F of the coefficient of variation of the age of each grain and its expected coefficient should be close to 1. As in the case of the population method, the calculations are repeated until the F value of a set of mineral grains becomes almost 1. (author)